A number of wiping products on the market consist of an absorbent fibrous web structure, or towelette, that is impregnated with a liquid to impart some desired attribute to its utility. For example, premoistened wipes employing cleansing lotions have become extremely popular for use in cleaning many portions of the human body; either to obtain a more thorough cleaning than can be achieved solely with a dry tissue, or for use under conditions where water, towels and the like are not readily available. One specific use for premoistened wipes is for cleaning excreta from the human anus, and usually after toilet paper has been used in the normal manner. In such an application the wiper is not a substitute for toilet paper but provides the final cleansing operation after the bulk of the excreta has been removed with the toilet paper. Impregnated wipes also are becoming extremely popular in the baby care field. Scott Paper Company, the assignee of this application, presently markets a baby wipe product under the trademark Baby Fresh.
Several prior art impregnated products, including the Baby Fresh product referred to above, are stacked and packaged in a sealed container. As part of the packaging operation the individual webs are folded, stacked and thereafter placed into a tub or similar container. It has been suggested to impregnate this product by spraying, printing or otherwise applying the additive onto a continuous web prior to cutting the web into discrete towelettes, or wipes, for subsequent folding and stacking into the container. Handling a wet web in the cutting, folding and stacking operations is usually a difficult, slow and inefficient process. In addition it is often more difficult to maintain sanitary conditions in a wet environment than in a dry environment. If equipment handling the wet web becomes contaminated, it can easily transmit the contaminants to the impregnated product. In a baby wipe product, for example, the contaminants can cause skin irritation and rashes.
In view of the above it should be appreciated that it is most desirable to cut, fold and stack the fibrous webs in a dry state, and thereafter add the liquid impregnating agent through a sanitary piping system. However, prior to this invention, there were several unsolved problems associated with such an impregnating technique. First a serious problem existed in introducing the impregnating liquid into the stack in a manner that completely saturated all of the sheets. This is a particularly significant problem when the individual sheets are of a low density, high bulk and highly absorbent construction of the type employed in the Baby Fresh product. Liquid applied to the upper sheet of such a stack tends to over saturate the top portion of the stack while leaving dry spots in the center portion of sheets in the interior of the stack. A second problem resides in providing sufficient residence volume within a tub containing the stack of webs so that the large volumes of liquid necessary to impregnate the stack can be introduced at a rapid rate into the tub, and thereafter be accommodated therein while the liquid is being absorbed into and through the stack.
It is also known in the art to add a liquid premoistening agent to individually packaged towelettes, as is evidenced by the patent to Clancy (U.S. Pat. No. 3,481,099) and Weinberger (U.S. Pat. No. 3,286,435). However, the techniques employed for impregnating individually packaged towelettes need not, and in fact do not deal with the problems associated with impregnating a stack of sheets.